Various types of shutoff valves have been proposed, including the valve disclosed in U.S. Pat. No. 7,036,441. The valve disclosed in this patent allows an operator to close the valve manually in the event of an emergency by pulling on a cable routed in close proximity of the operator, or automatically shuts the valve if the cable, which is typically attached to a vehicle towing the implement carrying the valve, is pulled by virtue of the towing and towed vehicle becoming disconnected or un-hitched. The '441 patent uses a spring loaded ball valve for closure which, when open, provides very little restriction to flow. The closure system uses a cable attached to a pin that releases the spring loaded ball valve when pulled. The cable, however, is difficult to adapt for both automatic and manual closure of the valve. This is because a cable routed for good automatic operation cannot easily be routed to the towing vehicle cab for operator manual operation. Similarly, a cable routed for good operator manual operation cannot be routed for proper automatic operation in the case of a vehicle un-hitch event. In addition, when the valve is left open for long periods, sticking associated with spring loaded ball valves becomes a problem affecting the reliability of the system.
The cable constraints and sticking ball valve issues of the '441 patent are overcome by the electrical release system disclosed in Nimberger U.S. Pat. No. 7,401,562 which discloses a poppet style valve. The poppet style shutoff valve, however, undesirably introduces significant flow restriction when the valve is open.
The disadvantages of the prior art are overcome by the present invention, an improved remotely operated shutoff valve is hereinafter disclosed.